The TK (TK-3) and TKS were Polish tankettes during the Second World War.

The TK (also known as the TK-3) tankette was a Polish design produced from 1931 that was based upon an improved chassis of the British Carden Loyd tankette. The TKS was an improved model with a new hull and a more powerful engine. The armour of the TK was up to 8 mm thick (10 mm on the TKS). In 1939, re-arming of the tankettes with 38FK 20 mm machine guns began, but only about 24 were completed before the outbreak of World War II.

On 6 November 1934 Estonia purchased 6 vehicles from Poland, with the contract deal worth over 180,000 krones. The deal also included one additional tracked-lorry, and a motorcycle was given free as a bonus.

The 575 TK/TKS tankettes formed the bulk of the Polish armoured forces before the outbreak of war. They suffered heavy losses during the Invasion of Poland, often being the only armoured fighting vehicles available. Due to their light armament of a single machine gun, they stood no chance in combat against German tanks, except the Panzer I, but their small size suited them for reconnaissance and infantry support. Only the handful of tankettes armed with 20 mm guns had a fighting chance against the enemy tanks; in one instance on 18 September 1939 a 20 mm gunned TKS with Nkm wz.38 FK commanded by Podchorazy or Officer Candidate in the rank of SFC Roman Orlik destroyed three German Panzerkampfwagen 35(t) tanks.